Capacitive measurement probe for measuring the level of a liquid and tank equipped with such a probe

Abstract

Capacitive measurement probe ( 6 ) for measuring the level of a liquid in a tank ( 1 ), of the type comprising a body ( 7 ) for mounting the probe and a first plate ( 8 ) which is supported by the body and is intended, together with a second plate ( 41 ), to form a measurement capacitor intended to be connected to an electrical voltage supply, which plates are intended to be partially immersed in the liquid and to define, between them, a space for receiving the liquid. The first plate ( 8 ) is mounted on the body so that it can be adjusted between at least a high measurement position and a low measurement position.

What is claimed is:  
     
       1. A capacitive measurement apparatus for measuring the level of a liquid in a tank comprising: 
       a probe comprising a first plate and a second plate, the plates forming a measurement capacitor to be connected to an electrical voltage supply, the plates to be partially immersed in the liquid and to define, therebetween, a space for receiving the liquid; and  
       a body supporting the first plate and electrically connecting with the second plate;  
       wherein the first plate is adjustably mounted on the body between at least a high measurement position and a low measurement position.  
     
     
       2. The apparatus according to claim  1 , wherein the first plate is slidable with respect to the body between the positions. 
     
     
       3. The apparatus according to claim  1 , wherein the second plate is adjustably mounted on the body between at least a high measurement position and a low measurement position. 
     
     
       4. The apparatus according to claim  3 , wherein the second plate is fastened to the first plate. 
     
     
       5. The apparatus according to claim  3 , wherein the second plate is tubular and slides telescopically with respect to the body. 
     
     
       6. The apparatus according to claim  3 , further comprising means for returning the second plate towards one of the positions. 
     
     
       7. The apparatus according to claim  6 , wherein the return means comprises an electrical connection connecting the second plate to the voltage supply. 
     
     
       8. The apparatus according to claim  1 , wherein the first plate is tubular and slides telescopically with respect to the body. 
     
     
       9. The apparatus according to claim  1 , further comprising means for returning the first plate towards one of the positions. 
     
     
       10. The apparatus according to claim  9 , wherein the return means comprises an electrical connection connecting the first plate to the voltage supply. 
     
     
       11. A storage system for a cryogenic fluid in liquid/vapour equilibrium comprising a storage tank equipped with a capacitive measurement apparatus for measuring the level of liquid in the tank, the apparatus placed in a cavity defined by walls of the tank, the apparatus comprising: 
       a probe comprising a first plate and a second plate, the plates forming a measurement capacitor to be connected to an electrical voltage supply, the plates to be partially immersed in the liquid and to define, therebetween, a space for receiving the liquid; and  
       a body supporting the first plate and electrically connecting with the second plate;  
       wherein the first plate is adjustably mounted on the body between at least a high measurement position and a low measurement position.  
     
     
       12. The system according to claim  11 , wherein one of the walls defining the cavity comprises the second plate. 
     
     
       13. The system according to claim  12 , further comprising an electronic processing unit connected to the measurement capacitor, the unit determining the level of the liquid and controlling means for supplying the tank with cryogenic liquid or for actuating an alarm. 
     
     
       14. The system according to claim  11 , further comprising an electronic processing unit connected to the measurement capacitor, the unit determining the level of the liquid and controlling means for supplying the tank with cryogenic liquid or for actuating an alarm.